A latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs, and will have one or two outputs. It is the basic storage element in sequential logic, and is particularly useful as static random access memory (SRAM) because the latch tends to maintain the data while powered without requiring periodic refreshes like dynamic random access memory (DRAM). Latches are a fundamental building block of digital electronics systems used in computers, communications, and many other types of systems.
Latches are used as data storage elements. A flip-flop stores a single bit (binary digit) of data and one of its two states represents a “one” and the other represents a “zero”. Such data storage can be used for storage of state, and such a circuit is described as sequential logic. A latch is level-sensitive, providing an output that is based on the polarity of the difference in inputs, permitting the latch to function as an analog to digital converter (ADC).
The comparison is the basic operation in an analog-to-digital converter (ADC). This operation is performed by the latched comparator, which works synchronously with the clock signal and indicates, through its digital output level, whether the differential input signal is positive or negative. A positive feedback mechanism regenerates the analog input signal into a full-scale digital level.